Trem-like 4, a type I transmembrane protein and a member of the TREM family, consists of a single extracellular Ig-like domain of the V-type, a transmembrane domain, and a short cytoplasmic domain. Trem-like 4 is expressed on macrophages in the spleen, and dendritic cells, especially CD8+ dendritic cells. It is proposed to regulate the immune response based on its expression profile. It has been reported that B7-H3 is a receptor and that the soluble form of Treml4 has a binding affinity to late apoptotic or necrotic cells.